Cirola collects racist and hateful comments via Twitter and Facebook, before tracing the location of those who posted the remark via geolocation data. Billboard space is then bought up near that person's home, where the comment is then posted for all to see - though their name and photo are pixelated for anonymity.

"Those people [who post abuse online] think they can sit in the comfort of their homes and do whatever they want on the internet," Criola's founder Jurema Werneck told the BBC. "We don't let that happen. They can't hide from us, we will find them."

The campaign was started after a black weather presenter became a target of racist abuse after her image was posted to the Facebook page of Nacional Journal, a prime-time news programme.

The billboard campaign has been running since the summer, receiving a mixed response from the public.